What causes cloud colors?

Cloud colors range from white to dark gray, almost black, even. Cloud colors depend on how thick the cloud is, how much sunlight shows through the cloud and in what angle solar radiation comes in through the cloud. 

Clouds can be very dark or colorful.

Sometimes clouds can be the colors of a rainbow or show iridescent colors, like in the case of iridescent clouds. Sometimes nacreous clouds, higher in the atmosphere than other clouds, can be breathtakingly colourful. Sunlight reflecting from tiny ice crystals high in the atmosphere causes the beautiful colors.

The thicker a cloud is, the less sunlight it lets through and the more solar radiation is reflected away in the upper and central levels of the cloud. A thundercloud, also called cumulonimbus, can reach from relative close to the ground to a height of up to 10 miles, and solar radiation is not able to travel through the cloud very well. This reduction of light makes thunderclouds look dark and menacing.

High-level clouds are light of color 

High-level clouds consist mostly of ice crystals and are thin and wispy, so they let a lot of sunlight through. High level clouds do not provide much cover for UV rays. Sometimes interesting halo effects can be seen in high-level clouds: halos and reflections are formed when moonlight shines through them at a certain angle.

Article last updated 2/25/2021, 8:12:00 AM